Field of the Invention
The present invention relates to an organic light emitting device, and more particularly, to a white organic light emitting device for enhancing emission efficiency.
Discussion of the Related Art
Recently, as society advances to the information-oriented society, the field of display devices which visually express an electrical information signal is rapidly advancing. Flat panel display (FPD) devices, having excellent performance in terms of thinning, lightening, and low power consumption, have been developed.
Examples of the FPD devices include LCD devices, plasma display panel (PDP) devices, field emission display (FED) devices, organic light emitting display devices, etc.
In particular, the organic light emitting display devices are self-illuminating devices. In comparison with other FPD devices, the organic light emitting display devices have a fast response time, high emission efficiency, high luminance, and a wide viewing angle.
An organic light emitting device includes an organic emission layer which is formed between two electrodes. An electron and a hole are injected from the two electrodes into the organic emission layer, and an exciton is generated by combining the electron with the hole. The organic light emitting device is a device using the principle that light is emitted when the generated exciton is dropped from an excited state to a ground state.
A related art organic light emitting display device includes a blue emission layer formed of a fluorescence material, for realizing white color. However, a quantum efficiency of an emission layer formed of a fluorescence material theoretically is about 25% of a quantum efficiency of an emission layer formed of a phosphorescence material. For this reason, the blue emission layer formed of a fluorescence material cannot show sufficient luminance in comparison with a phosphorescence material.